The subject matter disclosed herein generally relates to gas turbine engines and more particularly, to flow sleeves used with gas turbine engines.
At least some known gas turbine engines include a transition piece that extends between a combustor assembly and a turbine nozzle assembly. Such transition pieces channel combustion gases from the combustor assembly to the turbine nozzle assembly. To control an operating temperature of the transition piece, at least some known engines channel cooling air from a compressor towards the transition piece. More specifically, in at least some known gas turbine engines, the cooling air is channeled from the compressor into a plenum that circumscribes at least a portion of the transition piece. As the cooling air flows through the plenum, the transition piece is cooled. A portion of the spent cooling air is then channeled from the plenum into a cooling passage defined between a combustor liner coupled upstream from the transition piece and a flow sleeve extending around the combustor liner. Cooling air entering the cooling passage is channeled towards the combustor assembly.
To enhance the cooling of the transition piece, at least some known transition pieces include turbulence-promoting ribs or turbulators that extend outward from an outer surface of the transition piece. Other known transition pieces include an impingement sleeve that includes a plurality of impingement passages extending about the transition piece. Some known impingement sleeves include a scoop-like device that enables air to enter the impingement passages. Although such cooling features enhance cooling of a portion of the transition piece, operating temperature profiles of the transition piece for all operating conditions may not be fully predictable and some portions of the transition piece may require additional cooling. Retrofitting existing gas turbine engines with replacement transition pieces that include such cooling features may be expensive, time-consuming, and may require that the gas turbine engine be off-line for an extended period of time. Furthermore, such cooling features may increase thermal stresses in the transition piece which over time, may shorten a useful life of the transition piece. Therefore, methods and/or apparatus that facilitate a uniform cooling of a transition piece are desired.